1. Field of the Invention
The invention is directed to an improved fuel injection system for an internal combustion engine.
2. Description of the Prior Art
One fuel injection system known from German Patent Disclosure DE 198 53 103 A1 has a fuel reservoir and a high-pressure fuel pump, by which fuel is pumped into the fuel reservoir as a function of engine operating parameters. A prefeed pump is also provided, by which fuel is pumped out of a fuel tank to the intake side of the high-pressure fuel pump. A fuel metering device is also provided, for controlling the fuel quantity pumped into the fuel reservoir by the high-pressure fuel pump. The fuel metering device is disposed between the prefeed pump and the high-pressure fuel pump, so that by it, the fuel quantity pumped by the prefeed pump and delivered to the intake side of the high-pressure fuel pump is adjusted. Excess fuel quantity pumped by the prefeed pump is returned to the intake side of the prefeed pump. As a result, although the requisite drive power for the high-pressure fuel pump is limited because the high-pressure fuel pump pumps only the fuel quantity actually required into the reservoir, nevertheless, as a rule the prefeed pump pumps an excessive fuel quantity, which is returned again. This requires high drive power for the prefeed pump, and the fuel pumped is severely heated. Moreover, the fuel metering device is subjected to the pressure generated by the prefeed pump and must be correspondingly complicatedly sealed off.